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Tag Archives: vapor compression refrigeration

What is a Metering Device – Refrigeration Components


What is a Metering Device – Refrigeration Components

What you will learn from this article:
1) We will answer the question, “What is a metering device” by defining the various types of HVAC equipment that use different types of metering devices and why.
2) How the metering device is involved in the refrigeration cycle
3) A comprehensive list of metering devices defining the metering devices commonly used in HVAC
4) Lots of resource and related links to help you learn more about metering devices.

What is a Metering Device - TXV- Thermostatic Expansion Valve

TXV Metering Device for a Heat Pump

Depending on the type of HVAC air conditioning or heat pump system it is and the efficiency range of the system will depend on the type of metering device the system has installed by the HVAC manufacturer of the air conditioner or heat pump system. Lower efficiency HVAC air conditioner and heat pump models have fixed orifice types while higher efficiency systems have thermostatic expansion valves installed in the HVAC air conditioner or heat pump system. The thermostatic expansion valve is far more complex than the fixed orifice metering device as the thermostatic expansion valve metering device modulates the refrigerant flow based on the temperature of the refrigerant temperature in the evaporator coil. This allows a specific amount of refrigerant, based on demand, to be metered into the evaporator coil while the fixed orifice metering device allows the same amount of refrigerant to enter the enter the coil no matter the conditions or the demand. As the liquid refrigerant enters the metering device it changes temperature and pressure. A partial amount of the liquid refrigerant flashes into a refrigerant gas or vapor as it leaves the metering device and enters the evaporator coil.


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Evaporator Coil for Heat Pumps & Air Conditioners | HVAC Refrigeration


Old Evaporator Coil in a Rooftop Air ConditionerEvaporator Coil for Heat Pumps & Air Conditioners – the evaporator is responsible for absorbing heat into the coils and the refrigerant. The evaporator is an essential component of vapor compression refrigeration. This is usually done as result of passing air or water over the evaporator coil where a heat exchange process takes place. Heat leaves the air or water (whatever medium is used) and is absorbed into the coil and the liquid refrigerant. As more and more heat is absorbed by the evaporator coil and the refrigerant again changes state from a liquid to a refrigerant vapor. By the time the refrigerant leaves the evaporator coil the refrigerant should be all vapor and ready to be received again by the refrigeration compressor.


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The Condenser for Air Conditioners and Heat Pumps| HVAC Refrigeration


The Condenser for Air Conditioners and Heat Pumps - Trane Heat Pump Condenser

Trane Heat Pump Condenser

The Condenser for Air Conditioners and Heat Pumps

The condenser coil receives the high pressure high temperature refrigerant vapor from the compressor and immediately begins to remove heat from the refrigerant vapor. As the refrigerant vapor makes its way through the condenser coil more and more heat is removed and the refrigerant vapor changes state from a refrigerant vapor to a refrigerant liquid. While the liquid refrigerant changes temperatures from a higher temperature to a slightly lower temperature the pressure remains constant. As the refrigerant vapor leaves the condenser coil it makes it way to the metering device.


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HVAC Centrifugal Compressors | HVAC Refrigeration


HVAC Centrifugal Compressors

McQuay Chiller Uses HVAC Centrifugal Compressors

HVAC Centrifugal Compressors – Centrifugal compressors are used in many applications including pipeline transport of natural gas along with many other related applications including vapor compression refrigeration. These compressors have different operating limitations than the reciprocating compressor, the scroll compressor, and the rotary compressor. They an operating range where it operates efficiently however outside of this range, either the over or under that operating range, is basically useless. Other issues make them not ideal for use in certain applications because of the operating range issues.


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Rotary Compressors | Air Conditioning & Heating Systems


Rotary Compressors

Rotary Compressors – The rotary compressor used in HVAC applications for air conditioning and heating systems offer some of the most efficient air conditioner and heat pump systems one can find on the market. Despite the rotary compressor being a key component of an air source air conditioner or heat pump the efficiency offered by this compressor when used as a modulating compressor can exceed efficiency ratings of some geothermal systems. When the compressor is coupled with an inverter and the proper inverter control system the efficiency of the air source air conditioner or heat pump system spike to match those of some geothermal air conditioner or heat pump systems.


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MONDAY, July 06, 2015

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HVAC Tips: Helping You Learn

HVAC Preventive Maintenance: Just like a vehicle needs preventive maintenance, HVAC systems need a regular maintenance schedule. Having maintenance performed on your air conditioning and heating systems now can help you avoid costly repairs in the future. Air Conditioning and heating preventive maintenance also pays for itself by making the unit more efficient, safe, and reliable. Often, a technician can spot a ten dollar part that needs replacing now where if it is let go and not replaced, can cost you hundreds of dollars more in the future. The old phrase is true, "pay me a little now, or a lot later." I see it everyday. Basic maintenance on condensers and air handling units will save you money in the long run. If your local heating and cooling company offers maintenance agreements look into getting one for your home or business. Typically, companies offering maintenance agreements waive overtime charges for after hours or emergency calls and offer you reduced prices on parts. That is in addition to performing preventive maintenance twice annually.

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